1. Field of the Invention
The present invention broadly concerns an apparatus for holding and selectively releasing compressed air model rockets. More particularly, it is concerned with a model rocket launcher which is able to hold, pressurize, and launch rockets made from plastic bottles using water and air or an inert gas as a propulsion source.
2. Description of the Prior Art
Increased focus is being provided to hands-on experimentation and practice in the education of elementary and secondary students. Students are being provided with increased opportunities to use their imagination for development of projects in the field of science, and to complement classroom study with measurement of actual results.
One such project which has enjoyed wide acceptance involves the building and launching of so-called bottle rockets. As used herein, "bottle rockets" refers to rockets made from a bottle and which uses liquid such as water and a compressed gas as the propulsion source, and not to a fireworks rocket or other combustion device. Students use standard sized plastic (usually polyethylene terphthalate) bottles as a starting point for the rocket. Such bottles are commonly sold containing carbonated soft drinks in 16 oz, 20 oz, 24 oz, 1 liter, 2 liter and 3 liter sizes. Such used soft drink bottles are especially desirable because they are of a common, predetermined volume capable of handling moderate pressurization, are inexpensive, have a threaded neck of a common, standard size and configuration. Students typically glue or otherwise attach stabilizing fins to the bottle adjacent the threaded neck which serves as a nozzle and is pointed down during launching. The bottle is made more aerodynamic by the addition of a nose cone to the base, and a parachute or similar device may be deployed from the nose cone to retard descent. The bottle rocket thus created is at least partially filled with water, and air or a relatively inert gas such as carbon dioxide is used as a propellant. The bottle rocket is released from a launcher whereupon the compressed gas bears against the water, expelling it from the threaded neck and lifting the bottle rocket by the impulse force applied in the opposite direction.
One problem associated with existing bottle rocket launchers is that the attachment between the launcher for releasing the bottle rocket may only be at one side, causing only a single point of connection and possibly causing the bottle rocket to prematurely launch or launch in an undesired launch angle. Another problem with existing launchers is that they interfere with stabilizing fins which extend far below the nozzle. In addition, large or multistage bottle rockets may tip or fall out of the launcher while being pressurized. Another problem is leakage of the liquid propellant, typically water, past the seals during pressurization and while waiting the launch. Another problem is that bottle rockets must be pressurized while on the launcher. A further problem arises when the launch is prematurely triggered by an anxious student or other accident, which may result in an unsafe situation.
As a result, there has arisen the need for an improved bottle rocket launcher which can be safely and easily used in the field.